Molecular characterization of the hepatitis b virus in South Africa

Thesis submitted in compliance with the requirements for the degree of Doctor of Philosophy in the Department of Health Science at the University of the Witwatersrand Johannesburg 2001The hepatitis B virus (HBV) partitions into 6 genotypes (A-F) and a seventh putative genotype, genotype G, which has recently been described. As southern Africa is highly endemic for HBV infection and little is known of the molecular epidemiology of HBV in this part of the world, we determined the genotype of viral strains circulating in both rural and urban South Africa and rural Namibia. Two screening assays were used. The first was based on size and restriction fragment length polymorphism (RFLP) analysis of specific polymerase chain reaction (PCR) fragments amplified from the preS 1 and preS2 regions of the surface gene. The second method was an enzyme immunoassay (EIA) based serological determination of genotype which used monoclonal antibodies raised against genotype-specific epitopes in the preS2-region. Only genotypes A and D were found in significant numbers in South Africa. The urban specimens partitioned as follows: 69.6 percent genotype A, 3.6 percent genotype B, 7.1 percent genotype C, 16.1 percent genotype D and 3.6 percent genotype E. Rural specimens were all either genotype A (89.2 percent) or genotype D (10.8 percent).IT201